The DR PlotGeneralInformationThe importance of maintaining an accurate dead reckoning plot cannotbe overemphasized. Since other means of fixing your ships positionmay not always be available, a navigator must rely on a DR plot.If a ship made good the exact course and speed ordered, and there wasno wind or current, dead reckoning would, at all times, provide anaccurate indication of the ships position. A navigator must know theposition, or approximate position, to determine when to make changes incourse and/or speed, to predict the time of sighting lights or other aids tonavigation, and to identify landmarks.RulesWhen maintaining a DR plot, there are six rules that govern whatactions the QM should take. These rules are not subject tointerpretation, they are hard and fast. Often, when the ship is changingcourse it becomes tedious to maintain the DR plot. This is a given andknown fact; however, the importance of keeping the plot up to date cantbe stressed enough.These rules specify when a DR position shall be plotted:#Rule1.A DR position shall be plotted each hour on the hour.2.A DR position shall be plotted at the time of every coursechange.3.A DR position shall be plotted at the time of every speedchange.4.A DR position shall be plotted at the time of a fix or running fix.5.A DR position shall be plotted at the time of obtaining a singleLOP.6.A new course line shall be plotted from each new fix or runningfix.8-3